1. Field of the Invention
The present invention relates to the field of semiconductor integrated circuit (IC) manufacturing, and more specifically, to a structure with a low dielectric constant and a method of forming such a structure.
2. Discussion of Related Art
As design rules for integrated circuits (ICs) continue to shrink, more layers of metallization become necessary in the back end processing to connect the additional transistors fabricated in the semiconductor substrate during the front end processing. Dielectric films are needed to provide insulation between metal lines on the same level and between metal lines on different levels.
The dielectric films play an integral part in determining the performance and the reliability of a multilevel metal system. Reducing intermetal dielectric capacitance will decrease interconnect Resistance-Capacitance (RC) delay, thus allowing higher speeds to be achieved by the devices. Reducing capacitance will also decrease cross talk interference between metal lines and minimize Alternating Current (AC) power dissipation.
Many challenges are provided by the device topography and the thermal budget. The device topography may require the filling of dielectric films into gaps with high aspect ratios. The thermal budget of the diffusions and the metallurgy may limit the processing temperatures and times of the dielectric films.
Successful integration of dielectric films into a multilevel metal system requires careful consideration of the mechanical, chemical, and electrical properties of the dielectric films. The properties of dielectric films are strongly dependent on the deposition process. Silicon Dioxide is commonly chosen for the dielectric film because of its many desirable properties and the variety of deposition processes available. However, the dielectric constant of Silicon Dioxide is about 4.0 which is not low enough for advanced ICs that must operate at high frequencies.
Thus, what is needed is a structure with a low dielectric constant and a method of forming such a structure.